A video released on Wednesday that appears to show a police officer in New Jersey kicking a man shortly after he emerged, in flames, from a car accident has added a new dimension to an investigation into a police shooting.

The footage captured what may have been a case of mistaken identity. The man who came out from the flaming wreck was not the suspect who had just led Jersey City police on a miles-long car chase through the city on Sunday night, according to the Hudson County prosecutor’s office.

In a graphic video first released by Univision, the man, Miguel Feliz-Rodriguez, 28, appeared to be rolling on the sidewalk in an attempt to extinguish the fire that engulfed his torso. Esther Suarez, the county prosecutor, said he was an “innocent victim.”

The bystander filming the scene, Erik Roberto, 36, can be heard shouting: “Help him out! Help him out!” as a group of police officers approached Mr. Feliz.

Instead, one of the officers, whose gun was drawn, appeared to kick Mr. Feliz in the head.

After that, “they were dragging him to the street like he was an animal,” Mr. Roberto said in a phone interview. “I don’t think any human being should be treated in that way.”

The Hudson County prosecutor’s office opened an investigation into the episode before the video was released, as is common practice in cases of officer-involved shootings; the police had fired at the suspect, Leo Pinkston, during their pursuit. Mr. Pinkston is said to have caused at least one other car accident before crashing into Mr. Feliz. A spokesman for the prosecutor’s office said he could not comment on whether Mr. Pinkston was injured by any of the shots fired.

But the video has drawn a new level of scrutiny to the officers’ behavior.

“This video is now part of all the evidence we are considering as we investigate the actions of all individuals who were involved with the events of Sunday night in Jersey City,” Ms. Suarez said in a statement.

The episode began with a car chase shortly after 11 p.m. on Sunday. The police had tried to stop Mr. Pinkston, 48, in his vehicle, but he fled, evading the officers for about six miles before crashing into a utility pole and injuring Mr. Feliz, who had been driving on Tonnelle Avenue, the county prosecutor’s office said.

Both men were eventually transported for emergency medical care.

Mr. Pinkston has been charged with eluding officers and aggravated assault, both second-degree crimes.

Mr. Feliz remained hospitalized on Thursday.

“My brother at this moment is very bad,” the victim’s brother, Ramon Feliz, told Univision in Spanish. “He has 30 percent of his body burned.”

Jersey City police referred questions about the episode and continuing investigation to the city spokeswoman, Jennifer Morrill, who expressed “serious concerns about the conduct of this pursuit” but reserved judgment while the matter was being investigated by the county prosecutor.

“Once we clearly identify all the officers involved, we will be seeking termination in addition to any possible criminal penalties in appropriate cases,” she added in an emailed statement.

Mayor Steven Fulop of Jersey City said in a tweet on Wednesday that the episode was “unacceptable,” and raised the possibility of criminal charges against the officers involved.

But Carmine Disbrow, president of the Jersey City Police Officers Benevolent Association, said that the mayor’s “thoughts are with politics and not policing.”

“As it should be, this entire incident is being fully investigated,” Mr. Disbrow added in a statement. “Taking swift action isn’t always elegant, but this video clearly shows that the officers acted quickly to extinguish the flames, and pull this man out of harm’s way.”